Project Summary/Abstract This proposed research implements a differential susceptibility framework to investigate how physiological reactivity in toddlerhood moderates the association between early environmental factors and neural markers of anxiety of kindergarten-age children. This research question and its corresponding training plan allow the applicant to obtain extensive training with multiple methods of psychophysiological measurement and provides opportunities for professional development (i.e., conferences, manuscript preparation, grantsmanship), both of which are fundamental to the applicant's research-related career goals. An enhanced neurological error signal called error-related negativity (ERN) is robustly associated with anxiety in children and adults. ERN is measurable using electroencephalography (EEG). Parenting behaviors are linked to neurological development and anxiety risk, with some specific parenting behaviors recently associated with ERN. Despite the literature demonstrating a link between overprotective and supportive parenting and increased or decreased risk of childhood anxiety, respectively, these behaviors' relations to ERN have not been investigated. Further, differential susceptibility theory would suggest that the influence of parenting on ERN should only be considered in the context of the child's physiological reactivity, or a marker of the child's sensitivity and susceptibility to environmental influence. Aim 1: Identify how ERN in pre-kindergarten aged children is predicted by overprotective and appropriately supportive maternal parenting behaviors in toddlerhood, and how this relation changes when considering the child's cortisol reactivity as a moderator. It is expected that only those children with higher cortisol reactivity will be susceptible to their environment. That is, overprotective parenting and child cortisol reactivity will interact to predict enhanced ERN, whereas the interaction between greater cortisol reactivity and supportive parenting will predict decreased ERN. Secondly, temperamental inhibition, or a child's wary and fearful response to novelty, will be investigated as a behavioral indicator of dispositional physiological reactivity in toddlerhood. Aim 2: Identify how childhood ERN is predicted by overprotective and appropriately supportive maternal parenting behaviors in toddlerhood, and how this relation changes when considering the child's level of inhibition as a moderator. Similar to Aim 1, it is expected that only highly inhibited children will display an enhanced ERN when exposed to maternal overprotection or a decreased ERN when exposed to supportive maternal parenting. By determining the influence of specific parenting behaviors and the child's openness to their environment on neurological activity, we can determine the type of parenting behaviors in toddlerhood that are optimal for neurological development to reduce the risk of anxiety in kindergarten-aged children.